摘要:

The sampling functions needed to reconstruct from quadrature distributions the density matrix elements in the displaced Fock-state basis are determined as scaled and shifted pattern functionsfmnused to reconstruct the density matrix elements Qmnin the Fock-state basis. Having at hand the diagonal density matrix elements one can reconstruct any s-parametrized quasiprobability distribution via a simple weighted sum over these quantities. A smoothed Wigner function can be directly sampled from the measured quadrature distribution of the signal field. The corresponding sampling function is just a shifted and scaled version off00.

ISSN:0950-0340    

DOI:10.1080/09500349908231327

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Insertion of the expression for a Gaussian beam into Maxwell’s equations leads to four coupled equations governing the evolution of beam parameters in a logarithmically saturable nonlinear medium (LSNM). Analytical solutions to the coupled equations have been deduced for cases where the incident beam parameters slightly deviate from those of the spatial soliton. As a result, a detailed description to the Gaussian-type breath mode can be made. For general cases, a graphical analysis has been used to draw the main characteristics of the Gaussian-type breath mode propagating along the LSNM.

ISSN:0950-0340    

DOI:10.1080/09500349908231328

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A so-called cylindrical localized approximation, allowing one to speed up the evaluation of beam shape distributions in generalized Lorenz-Mie theory for circular infinitely long cylinders, has been previously introduced and, in the case of Gaussian beams, rigorously justified. In this paper, we examine and demonstrate the validity of this approximation for arbitrary shaped beams.

ISSN:0950-0340    

DOI:10.1080/09500349908231329

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The optical wave propagation within liquid crystal structures is addressed by the development of rigorous electromagnetic wave propagation methods. The demand of more refined optical wave modelling methods is driven by the fact that the currently used methods applied to liquid crystal devices rely on the stratified medium approximation. As a consequence devices with variations of the director orientation on the scale of the optical wavelength cannot be accurately analysed. An appropriate beam propagation method is developed to circumvent these limitations in the case of liquid crystal devices exhibiting the bend/splay deformation in the director profile. The method is a wide-angle scheme, and is therefore not restricted to the paraxial region; it is tested on tilted liquid crystal structures.

ISSN:0950-0340    

DOI:10.1080/09500349908231330

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper is concerned with the statistical distribution of the maximal hot spots of speckle patterns such as those generated by optical smoothing methods designed for inertial confinement fusion. It is proved that the maximal intensity at the first order is proportional to the logarithm of the ratio of the pulse volume over the mean hot spot volume. Nevertheless the complete description of the maximal intensity exhibits a quite important variance. Different ways for reducing either the maximal fluence or the maximal intensity are investigated, which are based upon time incoherence or polarization smoothing.

ISSN:0950-0340    

DOI:10.1080/09500349908231331

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We consider a single two-level atom driven by the output from a degenerate optical parametric oscillator. For squeezing bandwidths of the order of the natural atomic width and smaller, we report remarkable spectral profiles for the scattered light, including the existence of a narrow hole at line-centre. Under appropriate conditions, the spectrum may be both subnatural and narrower than the spectrum of the incident field, a phenomenon which does not depend upon strong coupling. To explain the role of the classical or non-classical nature of the driving field plays, we consider an alternative system which enables the atom to be driven by an arbitrary bandwidth light field with arbitrary two-photon correlations. Both numerical and analytic solutions are employed to provide physical insight. Surprisingly, spectral narrowing does not require squeezing: narrowed spectra appear for driving with a blackbody field. Then the atomic fluorescence can be expressed as the product of the atomic response with the incident spectrum. The resulting narrowing is maximized for incident bandwidths of the order of the natural width. However, the narrow hole at line-centre does require a non-classical driving field. For ideal squeezing, the fluorescence at line-centre vanishes. We test how robust the effects are to changes in experimentally pertinent factors such as the solid angle of coupling.

ISSN:0950-0340    

DOI:10.1080/09500349908231332

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In this paper, we experimentally measure the temporal evolution of amplitude restoration and thresholding in an all-optical regenerative memory. The memory architecture comprises two coupled all-optical switching gates and different wavelength optical pulses are used for clock and data sources. The all-optical gates are nonlinear interferometers incorporating semiconductor optical amplifiers as the nonlinear optical material. The concatenated response of these nonlinear interferometers provides the required square top transmission function that allows the stored optical pulses to be equalized in amplitude. The edge of the transmission function forms the threshold for pulse storage in the memory. We input a variable amplitude data packet into the memory and record the temporal evolution of the pulses with a fast real-time digitizing oscilloscope. Complete amplitude restoration of the pulses occurs after ∼5 circulations of the optical fibre memory loop. This measurement is in good agreement with the theoretical prediction and indicates that the square top transmission response could also be achieved for data ‚on the fly’ with a linear concatenation of only a few all-optical switching gates.

ISSN:0950-0340    

DOI:10.1080/09500349908231333

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We investigate nonlinear couplers whose operation is based on Raman or Brillouin scattering. A quantum approach is used. Strong coherent laser pumping is assumed and linearized Heisenberg-Langevin equations of motion are solved. The influence of linear coupling constants, losses and phase mismatches on the dynamical behaviour of the coupler is discussed. Quantum statistical properties of optical modes involved in the interaction are investigated within the framework of the generalized superposition of coherent signal and quantum noise. Most attention is devoted to the possibility of generation of non-classical light. It is shown that such light can be generated only in compound modes according to our model and influence of various parameters on the generation is discussed. Optimal conditions for the generation of squeezed light are found.

ISSN:0950-0340    

DOI:10.1080/09500349908231334

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We study the general statistical measures of covariance and correlation coefficient for noncommuting quantum observables as exemplified by position and momentum operators in quantum optics. High values of the position-momentum quantum correlation coefficient are achievable with two-photon coherent states and Schrödinger cat states of the electromagnetic field for parametric values which renounce quadrature squeezing. We discuss quantum-optical paradigms to detect these measures.

ISSN:0950-0340    

DOI:10.1080/09500349908231335

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A negative low-contrast electron beam resist X AR-N 7700/18 is introduced, which provides a nearly linear dose-to-depth curve at electron acceleration voltages below 20 kV, and is therefore an excellent material for fabrication of multilevel diffractive optics. Direct electron beam recording at 12.5kV is used to pattern analogue surface profiles in this resist, and proportional reactive ion etching (RIE) is employed to transfer the profile into the SiO2substrate. It is shown that errors in resist-profile scale can be corrected by proper adjustment of the radio-frequency power or chamber pressure in RIE. The reproducibility of the profile scale is better than 2%. Transmission-type blazed gratings, array illuminators, and pattern projection elements are demonstrated.

ISSN:0950-0340    

DOI:10.1080/09500349908231336

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor